In the prior art, there is a system in which a plurality of reflectors are disposed along the travelling path, and the reflectors are recognized by means of a laser scanner on an automatic guided vehicle to calculate their present position. When three reflectors can be recognized, the present position can be calculated using the principle of triangulation, therefore, the problem with this approach is that concerning whether such recognized reflector is to be specified which of the reflectors on the reflector map. In this case, this problem can be easily solved by assigning identification data such as bar codes to the reflectors, however, such reflectors are expensive and require much time to install. Therefore, in general, the reflectors must be identical.
In order to specify a reflector without assigning identification data to the reflector itself, the start position of an automatic guided vehicle is input to the automatic guided vehicle. First, presuming that the automatic guided vehicle starts from a known position, the recognized reflector is specified at the starting time. In subsequent recognition, the present position is assumed from the previous recognized position, and assuming that the reflector can be recognized for that position is recognized, the reflector is specified.
However, when using this technique, if a reflector is incorrectly recognized, it becomes impossible to recognize the exact position of the automatic guided vehicle, thus making it uncontrollable. In addition, it is time-consuming to input the present position during at the starting time. For example, presuming that the automatic guided vehicle starts up from a specific reset position, the automatic guided vehicle is manually driven and started up to that position, or it becomes necessary to manually input the present position at each position on the site. In any case, such work is time-consuming.
It is an object of the present invention to start up the automatic guided vehicle to an autonomous travelling without initial position data.
It is another object of the present invention to reduce the error rate of the recognized initial position of the automatic guided vehicle to a negligible value.
It is still another object of the present invention to provide a specific technique for obtaining the initial position of the automatic guided vehicle with a very low error rate.